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BOOK REVlR\\’S.
TEXT-BOOK
OF EMBRYOLOGY.
By Fredeyick Randolph Bailey and
Adam Marion Niller. New York : William Wood & Co., 1909 ;
pp. 6’72 ; 515 illustrations.
Like other recent text-books of embryology, this one was written
especially for the medical students with emphasis “upon those features which bear directly upon other branches of medicine.” The
authors of this book have, however, undertaken to “broaden its scope
and make it of greater value to the student of embryology and allied
sciences.’’
The volume is a good piece of book-making, as it is done in
America, being printed on heavy clay paper well adapted to halftones, in large, clear type. The illustrations are unusually clear and
the references are usually printed in full instead of being represented
by abbreviations explained by a legend below.
The authors have conscientiously describcd the development of
every organ of the body with no important exceptions and h v e
added a final chapter on teratogenesis. Each chapter is followcd
by practical suggestions giving the technique for the study of the
subjects described in the chapter, and by a list of the more important
literature for further study. To avoid repetition, there is an appendix
dealing with general technique. I n the chapters on organogenesis
there is included a brief account of the more important abnormalities
of development of the systems described. A very complete index of
33 pages concludes the book.
These are the bare statistics of this ambitious undertaking; one
would wish to be able to say of such a book, at the least, that it is
reliable and may be safely trusted as a guide to the subjects of which
it treats; but i t is necessary to record, with regret be it said, that
it is not a safe guide even in many matters of fact, and that many
of the generalizations are hasty and uncritical, or even absolutely
(466)
Book Revicws.
467
wrong. The general excellence of the illustrations, some 90 per
cent of which are borrowed, weighs but lightly in the balance.
The chapter on the nervous system, which is the work of Dr. 0. S.
Strong, is written with critical judgment and shows evidence of
good scholarship on every page ; the only criticism to be passed on it
in the opinion of the writer is that it is rather too abstract to be
readily intelligible to the class of students for whom it is intended;
but they cannot fail to profit by its study, and to the more advanced
student it is delightful reading. If the other chapters had been
up to this standard the book would deserve nothing but praise.
But the other chapters are characterized as a rule more by inclustry than by insight. This is especially shown in the first part of
the work, and, indeeed, in every place where knowledge of the general
principles of biology and of comparative anatomy and embryology
is required. When the authors reach the ground of anatomy, in
the narrower sense, they move more surely.
Some examples of the above criticisms should be given. I n Chapter I1 it is said of the frog‘s egg that “the dark side indicates an
excess of deutoplasm’, ; this is evidently a slip, the exact reverse being
intended. The authors then go on to say that “inasmuch as deutoplasm is heavier than cytoplasm an egg with polar differentiation, if
left free to revolve as in water, will assume a definite position with
the protoplasmic or animal pole above and the deutoplasmic or vegetative pole below.” I f the authors had studied the pelagic teleost
egg, where the reverse is the ease, they would not have made such
a sweeping statement; their rule is honored in the breach as well as
in the observance. The “membrana undulatoria or wavy membrane
of Birds,” p. 15 (referring to the spermatozoa), is a discovery of the
authors ; but perhaps Amphibia were meant.
The discussion of maturation in Chapter I11 is far from being
illuminating or even clear. It is hard to see why if “the maturation
of the male sex cells in the vast majority of forms is much more
difficult of demonstration than the maturation of the female sex
cclls” the number of studies on the former subject should exceed by
so many those on the latter. Nor can one understand why “it is
necessary to consider all the generations of cells from the mature
46s
The Anatomical Record.
spermatozoa back to the epermatogonia” in studying the maturation
of the male cells, if the same is not the case in the female sex cells.
This statement is repeated twice as a reason for the assumed difficulty
of studying the maturation of the inale sexual cells. The elassifioation of types of reduction into those with tetrad formation and those
without, which differ only in the fact that “each chromatin mags does
not show a differentiation into four pieces” in the latter case, but does
in the former, might be characterized as nalve.
In the chapter on fertilization, the occurrence of normal polysperiny ‘‘in some insects” is noticed, but its typical Occurrence in
some vertebrates (Selachia, Reptilia, Aves) with which the book
deals, is not mentioned. The exploded theory that the so-called fertilization membrane is a protection against polyspermy is upheld.
The chapter on cleavage is inexcusably careless in many respects,
bnt it is in the part dealing with some general features of cleavage
that the best gems of thought are found: we are told that “in a
spherical holobIastic egg the division plane may be in any direction,
but must bisect the mitotic figure at right angles to the long axis
of the spindle”; the fact of polarity, and the relation of tho first
cleavage plane to it, is ignored ; and the first part of the above statement is absolutely wrong. The distinction between radial and apiraf
cleavage appears always in the second cleavage, and may appear in
the tclophase of the first, a fact that the authors do not appear to
know. MoreoTer, the third division in spiral cleavage is inclined
nsually to the right, not to the left a3 the authors state. The term
“mornla” is no longer used by students of cleavage, except perhaps
as applied to the cleavage of the mammalian ovum, and the statement that “after the morula has become fully formed there appears
in it .a cleft or cavity due to separation of its cells” is wrong or
meaningless, as the reader chooses. “In eggs in which the cells
resulting from segmentation show greater inequality in size (due
to difference in yolkcontent) as in the frog, the segmentation cavity
is surrounded by several layers of cells”-thia ie true of the frog, but
the generalization is absurd (cf. Clepsine).
The subject of the germ-layers (Ch. VI) is taught by comparison,
homologizing the layers and the modes of their origin from Amphi-
lPook Rcviewa.
-I
oxus to man. This is one of the most difficult subjects in vertebrate
cmbryology; it involves more divergent views than any other. It
it perhaps unfortunate to hare placed before the student an account
Ivhich a trained embryologist cannot follow, but the student will a t
least be spared the pain of noting the frequent errors, e. g., the
description of the origin of the priniitire streak of birds from a
crescent which is said to be marginal, but was not so described by
its discoverer, and is not so figured by the authors; recent exact
accounts of the primitive streak are ignored, and Duval, Hertwig
and Eonnet are quoted, the two former at least incorrectly; the
reptiles are denied a primitive streak (p. 67). The archenteric
inragination of reptiles is wrongly stated to be marginal (p. 67)
though figured differently. The statements about the origin of the
mesoderm in reptiles and birds is extremely confusing, leading to
the coiiclusion that the mesoderm cells may be considered as derivatives of the protentoderm, whereas the figures show them correctly
as derived from the ectoderm.
The statement that “The amniotic folds from the beginning involve
the splanchnopleure” (p. 100) is another oversight ; of course somatoplenre is meant. I n the chick the head-fold of the amnion does
not begin on the first day as stated, but on the second.
P. 108. (‘The allantoic sac in most mammals is a very rudimentary structure”; even if the ungulates, in which the allantoic sac
is very large, had been excluded, this would be a very unsafe generalization.
P. 10s. “In all cases where the embryo is retained in the uterus
it (the chorion) forms a most highly specialized and complex structure
which in connection with the allantoic vessels establishes the communication between the mother and the embryo”; on p. 1 1 2 we are
told that monotremes and marsupials are dependent for their food
upon the yoIk stored up within the egg and that “in these two orders
the fetal membranes present essentially the same condition as in
Birds and Reptiles.” I f we put these two statements together are
we to infer that in the marsupials the embryo is not retained in the
iiterus? I s the student also to infer that marsupials in general hare
large yolk-bearing ova 1 I s the chorion of marsupials most highly
470
The ilnatoinical Record.
specialized and complex, or does it present essentially the same condition as in birds and reptiles? It is hard to say which is worse here,
the confusion or the errors.
To give further citations would be tedious, and perhaps unnecessary
to prove that the book requires a most thorough revision before it
can be recommended as a text-book of vertebrate embryology. Apart
from the above reasons for criticism, the writer cannot but feel that
the method of introducing students to the study of embryology
which consists in abstracting the salient points from the field of
comparative embryology is pedagogically wrong, although it is the
method of the great majority of text-books. I f it is necessary to
consider the problems of comparative embryology in an elementary
text, and it may be admitted that it is at least desirable, the development of some single form should run through the book as the main
stream of discussion, and i t should be given in su5cient detail to
stimulate the critical insight of the student ; the comparative statements may be made as side branches contributing to, and expanding
the main topic, and leading up to the generalizations.
F. R. Lillie.
EDIKGER’S
INTRODUCTION
TO THE STUDY
OX THE NERVOUS
SYSTEM.
(Edinger, L., Einfiihrung in die Lehre vom Bau und den Verrichtungen des Nervensystems.) Leipzig, F. C. W. Vogel, 1909.
The seventh edition of Edinger’s Lectures on the Central Nervous
System has quite outgrown the original purpose for which the
lectures were prepared, viz., an introduction to the internal organization of the central nervous system adapted for medical students and
practitioners. The work has become, in fact, a treatise on the cornparative anatomy and phylogeny of the vertebrate nervous system
not well adapted for the use of beginning students of the subject.
Accordingly, the author has just published a smaller and much more
elementary student’s manual.
The text of this little volume of 190 pages is largely rewritten;
it is not a mere condensation of the larger work. The treatment of
the subject is in plan similar to that of the earlier editions of the